Enhanced oil recovery (EOR) has become a fact of modern day oil extraction technology. EOR generally refers to techniques used for increasing the amount of crude oil that can be extracted from an oil field. There are a number of techniques presently used. Drill sites can be treated thermally or with sound to ease the flow of oil from the field to the well head. Chemical injection may be used to create chemical and physical phenomena which facilitate oil flow to the well head. The chemicals may be used to alter capillary pressure within the structures or alter the viscosity of the crude oil or other resident constituents.
By far the most commonly used approach to enhance recovery is gas injection. Supercritical gas is injected by way of injector pipes into oil bearing strata under high pressure. The high pressure gas pushes the oil to the producer pipes at the well head. The pressure of the gas provides two benefits in pushing the gas towards the producer pipes and in lowering the viscosity of the crude oil as the gas mixes with the crude oil. Gases such as CO2 and various natural gases are commonly used in liquid or supercritical form in gas injection.
If viscosity becomes an issue which it often is, the chemistry of the injected CO2 can be altered with the addition of various constituents. One class of constituents commonly added are surfactants. In particular, non-ionic surfactants have been used to provide a favorable viscosity to CO2 and enhance oil production. In application, a surfactant is added to the pressurized flow as the CO2 is injected into the oil field. The surfactants mix with CO2 to create a super critical mixture flowing at high pressure through the injector pipe.
While the mixture of CO2 and surfactants facilitates recovery, the pressurized nature of the mixture causes certain physical phenomena while moving through the injector pipe. One effect of the mixture flowing through the injectors is the deposition of sediment such as mineral and salt scale on the interior walls of the injector pipes. Diluents used in the surfactant mixture such as water, and brine, may also affect the formation of scale.
Given the nature of EOR and the absolute requirements that this processing be run at optimal levels, sediment or scale formation and, in turn, occlusion of injector piping has to be monitored. One monitoring device for monitoring wellbore fluids is disclosed in U.S. Pat. No. 6,880,402. The disclosed device combines a detection device and a manual descaling device but cannot simulate the actual materials which are forming on the injector piping interior wall.
As a result, there is a need for a more effective process useful in detecting the deposition of sediment on piping exposed to wellbore fluids.